This is a multicenter, pilot trial of brain interstitium Temozolomide concentration pre and post Regadenoson administration. This study will assess the feasibility of transient BBB disruption with Regadenoson. We expect to initially enroll up to 8 patients to obtain 5 evaluable patients over 12 months. If we detect greater than 50% increase in temozolomide brain interstitium AUC0-18 concentrations with Regadenoson, from baseline values on day 1 with temozolomide alone, in 40% of patients then we will expand the study cohort and enroll 8 additional patients to ensure a total of 10 evaluable patients.